Kinetic modelling of aldolase-catalyzed addition between dihydroxyacetone phosphate and (S)-alaninal

This paper is focused on the development of a kinetic model for an aldolase-catalyzed reaction. The aldol addition between dihydroxyacetone phosphate (DHAP) and (S)-benzyloxycarbonyl-alaninal ((S)-Cbz-alaninal) catalyzed by the four DHAP-dependent aldolases is a promising way for the synthesis of four complementary diastereoisomers with potential biological activity. The reaction catalyzed by fuculose-1-phosphate aldolase (FucA) conducts to a synthesis product with a 100% diastereomeric excess. A kinetic model has been proposed including both the synthesis and a parallel non-desired secondary reaction. The model involved an ordered two-substrate mechanism for the synthesis and non-competitive inhibition by (S)-Cbz-alaninal and competitive inhibition by methylglyoxal byproduct in both reactions. The values of the model kinetic parameters were determined and the model validated in batch and fed-batch synthesis reactions. The obtained model could be extended to explain the behavior of other class II DHAP-dependent aldolases and exploited in simulation for reactor design purposes.